Man is a tool-using animal. Without tools he is nothing, with tools he is all.

Quackery gives birth to nothing; gives death to all things.

In our wide world there is but one altogether fatal personage, the dunce,--he that speaks irrationally, that sees not, and yet thinks he sees.

Writing is a dreadful labor, yet not so dreadful as Idleness.

We are not altogether here to tolerate. We are here to resist, to control and vanquish withal.

Today is not yesterday: we ourselves change; how can our works and thoughts, if they are always to be the fittest, continue always the same? Change, indeed is painful; yet ever needful; and if memory have its force and worth, so also has hope.

I don't pretend to understand the Universe - it's a great deal bigger than I am.